I setup one QBO (Quickbooks Online) account to handle multiple LLCs. 

Theres a lot of place online to list like apartments.com, facebook marketplace, realtor.com, trulia, rent.com.

We currently have 105 units and are using a variety of excel, google docs/sheets/calendars, apartments.com (ads and rent collection), docusign and QuickBooks online (which we would like to keep). 

I agree that looking online is only going to get you so far, but I am trying to educate myself as much as possible before taking the next step.I am early on in the process where I am looking at areas that are long distance, as I live in a HCOL area.

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

Sadly, it’s sat on the market too long and I’m looking to get creative with bringing the attention of many buyers looking for a good deal on a property (online auction or something else with tons of attention??)

Well, what if the program was dropped from $10,000 to $2,000 but the entire guru coarse was through videos and online learning and it dropped the overall success rate to only 50% of the people buying only 1 house gaining only $40,000 in equity on that one house and after the course they felt somewhat confident that they could duplicate the process after the year was over.  

They are a huge online-only group and they loan up to 90% of home value. 

Check out other online guides available here: https://www.biggerpockets.com/guides3.

Unfortunately, ESA (Emotional Support Animal) letters are tricky, especially with how easy they are to get online.